Fix namespace and import

Author: GwendolenLynch

README.md

@@ -81,7 +81,10 @@ parent for each subclass.
 ###### Parent Class
 
 ```php
-use Camelot\DoctrineInheritanceMapping\Annotation\DiscriminatorEntry;
+<?php
+namespace App\Entity;
+
+use Camelot\DoctrineInheritanceMapping\Annotation\DiscriminatorMapItem;
 use Doctrine\ORM\Mapping as ORM;
 
 /**
@@ -102,7 +105,10 @@ optional, and has been omitted above for clarity.
 ###### Child(ren) Class
 
 ```php
-use Camelot\DoctrineInheritanceMapping\Annotation\DiscriminatorEntry;
+<?php
+namespace App\Entity;
+
+use Camelot\DoctrineInheritanceMapping\Annotation\DiscriminatorMapItem;
 use Doctrine\ORM\Mapping as ORM;
 
 /**